A damage steel beam full life operation and maintenance system and an operation and maintenance method
By monitoring the strain and temperature changes of shape memory alloys using fiber optic grating sensors and thermocouples, and combining this with a computer control system and excitation components, the problem of real-time monitoring and compensation for prestress loss in steel beams was solved, enabling full-life-cycle maintenance of damaged steel beams.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TONGJI UNIV
- Filing Date
- 2026-03-26
- Publication Date
- 2026-06-12
AI Technical Summary
Existing technologies cannot effectively monitor and proactively compensate for prestress loss in steel beams during service, especially prestress loss in complex or damaged components, and conventional methods cannot accurately measure the recovery stress changes of shape memory alloys (SMA).
Fiber grating sensors (FBG) and thermocouples are used to monitor strain and temperature changes in the SMA. Combined with a computer control system, recovery stress loss is predicted. The SMA is repeatedly excited by an excitation component to compensate for prestress loss. The evolution of recovery stress is predicted using the Lagoudas model.
It enables intelligent operation and maintenance of damaged steel beams throughout their entire life cycle, ensuring the performance stability and accurate monitoring of the reinforcement system throughout its entire life cycle through real-time monitoring and proactive compensation for prestress loss.
Smart Images
Figure CN122192916A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of civil engineering technology, specifically relating to a whole-life operation and maintenance system and method for damaged steel beams. Background Technology
[0002] Shape memory alloys (SMAs) are a type of smart alloy material with a wide range of applications. Their most prominent material property is the shape memory effect (SME), which means that an SMA stretched at room temperature can recover its initial geometric shape after being heated and activated. This process involves microscopic metallic phase transformations. By constraining the deformation of the SMA during the activation process, a corresponding recovery stress can be obtained. In the field of structural reinforcement, constraining the deformation of the SMA during activation and obtaining the corresponding recovery stress provides a more convenient method for applying prestress.
[0003] In actual engineering, the stress conditions of structures are quite complex. The performance of steel components deteriorates continuously during long-term service, and the prestress in the reinforcement system inevitably suffers loss. Common prestressed reinforcement systems can only implement over-tensioning measures during the prestressing process to offset potential subsequent prestress losses, and cannot actively compensate for prestress losses that have already occurred during service. Research shows that stretched SMAs can be repeatedly activated. This property provides a theoretical basis for compensating for prestress losses in the reinforcement system by repeatedly activating SMAs during service. By setting a reasonable multiple activation scheme, intelligent maintenance throughout the entire life cycle of the component can be achieved. However, the recovery stress of the SMA in the reinforcement system cannot be directly measured. The common method is to calculate the recovery stress of the SMA based on the strain data of the reinforced component and the deformation coordination within the reinforcement system. For complex asymmetric or damaged components, this calculation is cumbersome and cannot be calculated in real time according to the damage development of the component during service. In addition, the activation process of SMAs is accompanied by high temperatures, and conventional resistance strain gauges have large errors, making it impossible to accurately measure the strain changes of the SMA from pre-tensioning to activation and then to the subsequent service stages. Summary of the Invention
[0004] In view of this, the purpose of this invention is to provide a full-life-cycle operation and maintenance system and method for damaged steel beams. Utilizing the material properties of SMA and combining it with fiber optic grating sensors to monitor the strain changes of SMA throughout the entire process, a computer control system predicts the recovery stress loss of SMA during service caused by fatigue loads, temperature changes, or a single overload. When the loss threshold is reached, the SMA is repeatedly excited, and the evolution of the recovery stress of the SMA after each repeated excitation is re-predicted, thereby achieving intelligent operation and maintenance of damaged steel beams throughout their entire life cycle.
[0005] To achieve the above objectives, the present invention provides the following technical solution: A life-cycle maintenance system for damaged steel beams includes: a reinforcement component, a sensing component, an excitation component, and a computer control system; The reinforcement assembly includes an anchoring device and an actuating device. The anchoring device is used to anchor the end of the SMA and fix it to the steel beam. The actuating device is located between the two anchoring devices. One end of the actuating device is fixed to the lower flange of the steel beam, and the other end is in contact with the SMA. The actuating device is used to push the SMA and adjust the strain of the SMA. The sensing components include a FBG and a thermocouple, both of which are mounted on the surface of the SMA. The FBG is used to monitor strain changes throughout the entire lifespan of the SMA, while the thermocouple is used to monitor temperature changes of the SMA during the excitation process and service phase. The excitation component is used to excite the SMA; The computer control system is used to store and analyze data from each sensing component, and predict the evolution of recovery stress during service based on the temperature and strain changes of the SMA. When the loss value reaches the set threshold, the SMA is repeatedly excited by the excitation component to make up for the loss of recovery stress.
[0006] As a further preferred embodiment of the present invention, the actuating device continues to stretch the SMA after the SMA reaches the maximum excitation temperature corresponding to the current pre-stretch strain value, thereby increasing its upper limit of excitation temperature and obtaining higher recovery stress.
[0007] As a further preferred embodiment of the present invention, the FBG in the sensing component is used to monitor strain changes throughout the entire lifespan of the SMA, including the pre-stretching and excitation processes, as well as SMA strain changes during service due to fatigue loads, temperature changes, or a single overload, and the FBG is fixed to the SMA surface; the thermocouple in the sensing component is used to monitor SMA temperature changes during the excitation process and during service due to changes in ambient temperature; the sensing principle of the FBG is as follows: In the formula, The wavelength of the reflected light from the grating is 1. This represents the change in the wavelength of the reflected light. and These are the temperature sensitivity coefficient and the strain sensitivity coefficient, respectively. and These represent the temperature change and strain change, respectively. Strain and temperature changes alter the wavelength of the reflected light in the grating, and the corresponding temperature and strain changes can be obtained by measuring the wavelength change of the reflected light and performing decoupled calculations.
[0008] As a further preferred embodiment of the invention, the FBG and the thermocouple are arranged close together, so that the temperature at the thermocouple point is the same as the temperature at the FBG point, thus maximizing the temperature change measured by the thermocouple. As a known quantity, the strain change of the SMA is calculated using the following formula: As a further preferred embodiment of the present invention, the computer control system includes a data processing module and a loss prediction module; The data processing module is used to store and analyze the monitoring data of the sensing components, including the strain and temperature changes of the SMA, wherein the strain of the SMA is obtained through decoupling calculation; The loss prediction module uses the Lagoudas model to predict the recovery stress loss during the service phase of the SMA based on the monitored strain and temperature change data, and determines whether the recovery stress loss reaches the preset threshold.
[0009] As a further preferred embodiment of the present invention, the prediction of the recovery stress loss of the SMA using the Lagoudas model in the loss prediction module includes the following steps: The change in martensite content of SMA during the pre-stretching process is predicted, and the corresponding stress-strain relationship is given, so as to obtain the initial martensite content and stress state of SMA after pre-stretching. Based on the obtained initial martensite content and stress state, the change in martensite content of SMA during the excitation process is predicted, and the initial recovery stress generated by SMA under constraint conditions after excitation is calculated. Based on the obtained initial recovery stress and corresponding material state, the change in martensite content of the SMA during service is predicted, and the evolution of recovery stress during the service stage is calculated. This process adopts a back-mapping algorithm. First, elastic assumptions are made in the current calculation step, and the trial stress increment is obtained according to the strain increment. The trial stress increment is substituted into the thermodynamic criterion. If the phase transformation condition is not met, the trial stress increment is accepted and the next calculation step is entered. If the phase transformation condition is met, the consistency residual equation about the martensite volume fraction is solved iteratively to obtain the phase transformation strain component and elastic strain component in the current strain increment, and the true stress increment is calculated. The evolution of recovery stress of the SMA during the service stage is obtained by superimposing the stress increments in each calculation step.
[0010] As a further preferred embodiment of the present invention, the martensite volume fraction The consistency residual equation is shown below: In the formula, This represents the change in martensite volume fraction. For about Consistency residual equation Thermodynamic driving force The critical mechanical driving force that triggers the phase transition.
[0011] A method for the whole life cycle maintenance of damaged steel beams, the method includes the following steps: S1. Install SMA and reinforcement components: Fix the SMA to the steel beam using anchoring devices and install the actuation device; S2. Install the sensing components: Fix the FBG and thermocouple to the SMA surface and ensure that the FBG measuring point and the thermocouple measuring point are within the same temperature range; S3, Pre-stretched SMA: The SMA is stretched to the set pre-stretch strain by adjusting the actuation amount of the actuation device; S4. Excite the SMA: The SMA is excited to the set target excitation temperature through the excitation component to achieve the application of prestress; S5. Predict the recovery stress loss of the SMA in the initial state: Calculate the evolution of the recovery stress of the SMA during service based on the loss prediction module in the computer control system. S6. Repeated SMA activation during service: Set a recovery stress loss threshold based on the predicted recovery stress loss. If the threshold is reached, the recovery stress loss is compensated by repeated SMA activation. S7. Predict the recovery stress loss of SMA after repeated excitation: Based on the repeated excitation of SMA during service, the loss prediction module is used to update the recovery stress evolution of SMA after each repeated excitation, so as to realize intelligent operation and maintenance of steel beam throughout its entire life cycle.
[0012] The beneficial effects of this invention are as follows: (1) Life-cycle maintenance: By making full use of the material properties of SMA, prestress can be easily applied during the construction phase and prestress loss can be actively compensated during service. At the same time, combined with the high adaptability and anti-interference ability of FBG, the performance of the reinforcement system can be accurately monitored in all aspects throughout the construction and service process, so as to achieve life-cycle maintenance.
[0013] (2) Intelligent interaction; Based on the real-time temperature and strain changes of SMA, the phase transformation process of SMA during construction and service is calculated, and the evolution of recovery stress of SMA under initial state and after each repeated excitation is predicted. The subsequent reinforcement strategy can be optimized according to the prediction results to achieve intelligent interaction. Attached Figure Description
[0014] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a schematic diagram illustrating the structure and working principle of the operation and maintenance system of this invention; Figure 2 This is a schematic diagram of the FBG arrangement of the present invention; Figure 3 This is a schematic diagram of the calculation process for the pre-stretching process of the present invention; Figure 4 This is a schematic diagram of the calculation process for the excitation process of the present invention; Figure 5 This is a schematic diagram of the "prediction-correction" calculation process during the service phase. Figure 6 This is a schematic diagram of the closed-loop control of the operation and maintenance system of the present invention. Detailed Implementation
[0015] like Figures 1-6 As shown, the life-cycle maintenance system for damaged steel beams described in this invention mainly includes a SMA (Steel Beam Assembly), a reinforcement component, a sensing component, an excitation component, and a computer control system. The reinforcement component includes anchoring devices and actuation devices; the sensing devices include fiber optic grating (FBG) sensors and thermocouples; the excitation component can be a current excitation device or a common excitation device such as a heating pad. The SMA is fixed to the component by anchoring devices at both ends; the actuation device is located between the anchoring devices at both ends and is used to adjust the strain of the SMA. The strain change of the SMA throughout its life cycle (including pre-tensioning, excitation, and service) is monitored by the FBG, and the temperature of the SMA during the excitation process and service stage is monitored by thermocouples. The computer control system is used to store and analyze data from each sensing component and predict the evolution of recovery stress during service based on the temperature and strain changes of the SMA. When the loss value reaches a set threshold, the SMA can be repeatedly excited by the excitation component to compensate for its recovery stress loss.
[0016] The reinforcement component in this invention consists of an anchoring device and an actuating device. The anchoring device is used to anchor the ends of the SMA and fix them to the steel beam. The anchoring device and the steel beam should be connected in a non-destructive manner to avoid opening holes in the steel beam flange. The actuating device is located between the two anchoring devices and is also fixed to the lower flange of the steel beam in a non-destructive manner. It is used to push the SMA sheet, adjust the strain of the SMA, and achieve pre-stretching of the SMA on the reinforced steel beam. After reaching the maximum excitation temperature corresponding to the current pre-stretch strain value, the SMA can be further stretched to increase its upper limit of excitation temperature, thereby obtaining a higher recovery stress.
[0017] The sensing components in this invention include a fiber optic girders (FBG) and thermocouples. The FBG is used to monitor strain changes throughout the entire lifespan of the SMA, including pre-stretching and excitation processes, as well as strain changes during service due to fatigue loading, temperature changes, or a single overload. The FBG is fixed to the SMA surface, and its arrangement is as follows: Figure 2 As shown. Thermocouples are used to monitor SMA temperature changes due to ambient temperature variations during the excitation process and service life. The sensing principle of FBG is as follows: In the formula, The wavelength of the reflected light from the grating is 1. This represents the change in the wavelength of the reflected light. and These are the temperature sensitivity coefficient and the strain sensitivity coefficient, respectively. and These represent the temperature change and strain change, respectively. That is, strain and temperature changes alter the wavelength of the reflected light in the grating. By measuring the wavelength change of the reflected light and performing decoupled calculations, the corresponding temperature and strain changes can be obtained.
[0018] In this invention, the FBG and thermocouple should be arranged as close as possible to ensure that the temperature at the thermocouple point is the same as the temperature at the FBG point. This allows the temperature change Δ measured by the thermocouple to be accurately measured. T As a known quantity, the strain change of the SMA is calculated using the following formula: In this invention, the excitation component can use common heating systems such as ceramic pad heating devices or current heating devices. At the same time, during the excitation process, it is necessary to take good heat insulation and insulation measures between the SMA, the reinforcement component, and the steel beam.
[0019] The computer control system in this invention consists of a data processing module and a loss prediction module. The data processing module stores and analyzes monitoring data from the sensing components, including strain and temperature changes of the SMA (Strain Modulator-Modulator), where the SMA strain is obtained through decoupled calculations. In the loss prediction module, based on the monitored SMA strain and temperature change data, the Lagoudas model is used to predict the recovery stress loss of the SMA during its service life. The thermodynamic criterion used to determine whether a phase transition has occurred is: In the formula, and These represent the thermodynamic driving forces in the forward and reverse phase transition processes, respectively. and These represent the critical thermodynamic driving forces that trigger the forward and reverse phase transitions, respectively.
[0020] The prediction of recovering stress loss in SMA mainly includes the following processes: (1) Predict the change in martensite content of SMA during the pre-stretching process and give the corresponding stress-strain relationship. This process includes two stages: loading and unloading. The calculation process is shown in [reference]. Figure 3 .
[0021] (2) Predict the change in martensite content of SMA during the activation process and calculate the recovery stress during the activation process. The calculation process is as follows: Figure 4 .
[0022] (3) Predict the change in martensite content of SMA during service and calculate the evolution of recovery stress during the service stage. The change in martensite content and the corresponding evolution of recovery stress in this process are calculated using the back-mapping algorithm. First, an elastic assumption is made in the current calculation step. The stress increment is obtained based on the strain increment. The stress increment is substituted into the thermodynamic criterion. If the phase transformation condition is not met, it means that the elastic assumption is valid in the current calculation step. The stress increment is accepted and the next calculation step is entered. Conversely, if the phase transformation condition is met, it means that the elastic assumption is not valid in the calculation step. The phase transformation strain component corresponding to the current strain increment needs to be calculated iteratively. The iterative process needs to satisfy the requirements regarding the martensite volume fraction. Consistency residual equation: In the formula, This represents the change in martensite volume fraction. For about Consistency residual equation Thermodynamic driving force The critical mechanical driving force that triggers the phase transition.
[0023] This allows us to obtain the phase transformation strain component and elastic strain component corresponding to the current strain increment, and calculate the true stress increment. The calculation flow of the "prediction-correction" process described in the above-mentioned return mapping algorithm is as follows: Figure 5 As shown, the evolution of the recovery stress of the SMA during service can be obtained by superimposing the stress increments within each calculation step.
[0024] This invention achieves data interaction through a "sensing component—computer control system—excitation component," and its corresponding closed-loop control process is as follows: Figure 6 As shown.
[0025] The operation and maintenance method of the whole life operation and maintenance system for damaged steel beams described in this invention is as follows: (1) Install SMA and reinforcement components: Fix SMA to steel beam with anchoring device and install actuation device; (2) Install the sensing components: Fix the FBG and thermocouple to the SMA surface and ensure that the two FBG measuring points and the thermocouple measuring points are within the same temperature range; (3) Pre-stretching SMA: The SMA is stretched to the set pre-stretch strain by adjusting the actuation amount of the actuation device; (4) Excitation of SMA: The SMA is excited to the target excitation temperature through the excitation component to achieve the application of prestress; (5) Predict the recovery stress loss of the SMA in the initial state: Calculate the evolution of the recovery stress of the SMA during service based on the loss prediction module in the computer control system; (6) Repeated SMA stimulation during service: Set a recovery stress loss threshold based on the predicted recovery stress loss. If the threshold is reached, the recovery stress loss is compensated by repeated SMA stimulation. (7) Predict the recovery stress loss of SMA after repeated excitation: Based on the repeated excitation of SMA during service, the recovery stress evolution of SMA after each repeated excitation is updated using the loss prediction module, so as to realize intelligent operation and maintenance of steel beam throughout its entire life cycle.
[0026] This invention fully utilizes the material properties of SMA (Superficial Moisture Asphalt), enabling convenient application of prestress during construction and proactive compensation for prestress loss during service. Combined with the high adaptability and anti-interference capabilities of FBG (Fully Fastened Grafted Gear), it allows for comprehensive and precise monitoring of the reinforcement system's performance throughout construction and service, achieving full life-cycle maintenance. Based on real-time temperature and strain changes in SMA, the phase transition process of SMA during construction and service is calculated, predicting the evolution of recovery stress in the initial state and after each repeated excitation. Subsequent reinforcement strategies can be optimized based on the prediction results, achieving intelligent interaction.
Claims
1. A life-cycle maintenance system for damaged steel beams, characterized in that, include: Rugged components, sensing components, excitation components, and computer control systems; The reinforcement assembly includes an anchoring device and an actuating device. The anchoring device is used to anchor the end of the SMA and fix it to the steel beam. The actuating device is located between the two anchoring devices. One end of the actuating device is fixed to the lower flange of the steel beam, and the other end is in contact with the SMA. The actuating device is used to push the SMA and adjust the strain of the SMA. The sensing components include a FBG and a thermocouple, both of which are mounted on the surface of the SMA. The FBG is used to monitor strain changes throughout the entire lifespan of the SMA, while the thermocouple is used to monitor temperature changes of the SMA during the excitation process and service phase. The excitation component is used to excite the SMA; The computer control system is used to store and analyze data from each sensing component, and predict the evolution of recovery stress during service based on the temperature and strain changes of the SMA. When the loss value reaches the set threshold, the SMA is repeatedly excited by the excitation component to make up for the loss of recovery stress.
2. The life-cycle maintenance system for damaged steel beams according to claim 1, characterized in that: After the SMA reaches the maximum excitation temperature corresponding to the current pre-stretch strain value, the actuation device continues to stretch the SMA to increase its upper limit of excitation temperature and obtain a higher recovery stress.
3. The life-cycle maintenance system for damaged steel beams according to claim 1, characterized in that: The FBG in the sensing assembly is used to monitor strain changes throughout the SMA's lifespan, including pre-stretching and excitation processes, as well as SMA strain changes during service due to fatigue loading, temperature changes, or a single overload. The FBG is fixed to the SMA surface. The thermocouple in the sensing assembly is used to monitor SMA temperature changes during the excitation process and during service due to changes in ambient temperature. The sensing principle of the FBG is as follows: In the formula, The wavelength of the reflected light from the grating is 1. This represents the change in the wavelength of the reflected light. and These are the temperature sensitivity coefficient and the strain sensitivity coefficient, respectively. and These are the temperature change and strain change values, respectively; That is, strain and temperature changes will change the wavelength of the reflected light in the grating. The corresponding temperature and strain changes can be obtained by measuring the wavelength change of the reflected light and decoupling the calculation.
4. The life-cycle maintenance system for damaged steel beams according to claim 3, characterized in that: The FBG (Fan-Free Geometry) is placed close to the thermocouple so that the temperature at the thermocouple point is the same as the temperature at the FBG point, thus ensuring that the temperature change measured by the thermocouple is the same. As a known quantity, the strain change of the SMA is calculated using the following formula: 。 5. The life-cycle maintenance system for damaged steel beams according to claim 1, characterized in that: The computer control system includes a data processing module and a loss prediction module; The data processing module is used to store and analyze the monitoring data of the sensing components, including the strain and temperature changes of the SMA, wherein the strain of the SMA is obtained through decoupling calculation; The loss prediction module uses the Lagoudas model to predict the recovery stress loss during the service phase of the SMA based on the monitored strain and temperature change data, and determines whether the recovery stress loss reaches the preset threshold.
6. The life-cycle maintenance system for damaged steel beams according to claim 5, characterized in that: The prediction of the recovery stress loss of SMA using the Lagoudas model in the loss prediction module includes the following steps: The change in martensite content of SMA during the pre-stretching process is predicted, and the corresponding stress-strain relationship is given, so as to obtain the initial martensite content and stress state of SMA after pre-stretching. Based on the obtained initial martensite content and stress state, the change in martensite content of SMA during the excitation process is predicted, and the initial recovery stress generated by SMA under constraint conditions after excitation is calculated. Based on the obtained initial recovery stress and corresponding material state, the change in martensite content of the SMA during service is predicted, and the evolution of recovery stress during the service stage is calculated. This process adopts a back-mapping algorithm. First, elastic assumptions are made in the current calculation step, and the trial stress increment is obtained according to the strain increment. The trial stress increment is substituted into the thermodynamic criterion. If the phase transformation condition is not met, the trial stress increment is accepted and the next calculation step is entered. If the phase transformation condition is met, the consistency residual equation about the martensite volume fraction is solved iteratively to obtain the phase transformation strain component and elastic strain component in the current strain increment, and the true stress increment is calculated. The evolution of recovery stress of the SMA during the service stage is obtained by superimposing the stress increments in each calculation step.
7. The life-cycle maintenance system for damaged steel beams according to claim 6, characterized in that: The martensite volume fraction The consistency residual equation is shown below: In the formula, This represents the change in martensite volume fraction. For about Consistency residual equation Thermodynamic driving force The critical mechanical driving force that triggers the phase transition.
8. A method for the whole-life operation and maintenance of damaged steel beams, characterized in that, Using the full-life-cycle maintenance system for damaged steel beams as described in any one of claims 1-7, the method includes the following steps: S1. Install SMA and reinforcement components: Fix the SMA to the steel beam using anchoring devices and install the actuation device; S2. Install the sensing components: Fix the FBG and thermocouple to the SMA surface and ensure that the FBG measuring point and the thermocouple measuring point are within the same temperature range; S3, Pre-stretched SMA: The SMA is stretched to the set pre-stretch strain by adjusting the actuation amount of the actuation device; S4. Excite the SMA: The SMA is excited to the set target excitation temperature through the excitation component to achieve the application of prestress; S5. Predict the recovery stress loss of the SMA in the initial state: Calculate the evolution of the recovery stress of the SMA during service based on the loss prediction module in the computer control system. S6. Repeated SMA activation during service: Set a recovery stress loss threshold based on the predicted recovery stress loss. If the threshold is reached, the recovery stress loss is compensated by repeated SMA activation. S7. Predict the recovery stress loss of SMA after repeated excitation: Based on the repeated excitation of SMA during service, the loss prediction module is used to update the recovery stress evolution of SMA after each repeated excitation, so as to realize intelligent operation and maintenance of steel beam throughout its entire life cycle.